customer3: EVENT2 -> conference

Keith is going to try to use Zulip again during the next conference;
CoNEXT, so we need to rebrand. We use generic language here so that
we don't need to do this every time.

(imported from commit c97f7d4bb84f2dfd4c6db265884ba17be0fd5677)

templates/zerver/accounts_home.html

@@ -20,7 +20,7 @@ $(function () {
 
         <div class="register-form">
             <p class="lead">
-              <span id="customer3-pitch" style="display: none;">Participate in the real-time EVENT2 discussion using Zulip!</span>
+              <span id="customer3-pitch" style="display: none;">Participate in the real-time conference discussion using Zulip!</span>
               <div class="register-page-header">Let's get started…</div>
             </p>
             <form class="form-inline" id="send_confirm" name="email_form"

templates/zerver/register.html

@@ -19,7 +19,7 @@ Form is validated both client-side using jquery-validate (see signup.js) and ser
 
 {% ifequal company_name "customer3.invalid" %}
     <p style="margin-top: 30px;">
-    CUSTOMER3 is using <a href="/hello">Zulip</a> for real-time chat during EVENT2.
+    CUSTOMER3 is using <a href="/hello">Zulip</a> for real-time chat during this conference.
     </p>
 {% endifequal %}